# 键值对  可变

ab = {'k1': 'v1', 'k2': 'v2', 'k3': 'v3', 'k4': 'v4'}

print(ab)
print(ab['k3'])
del ab['k1']
for k, v in ab:
    print(k, '=', v)

if 'k4' in ab:
    print('k4=', ab['k4'])
